1. Field of the Invention
The present disclosure relates to methods and systems for fast purging of data from, for example, change data tables within database applications without the use of the SQL DELETE statement.
2. Brief Description of Related Developments
As described in the above identified pending patent applications, a subscriber of change data capture system captures all the updates including SQL INSERT, DELETE and UPDATE statements that occur to interesting tables in a relational database, and stores the change data in a set of relational tables referred to as change tables.
As described in the above pending patent applications, the subscriber (user) of the Change Data Capture systems calls the EXTEND_WINDOW and PURGE_WINDOW interfaces to consume data from change tables. This also indicates to the system that the subscriber has finished with some of the change data, and therefore that data can be safely deleted from the system. It is important to delete change data once all the subscribers are finished with it, due to the large amount of change data that is constantly added to change tables. It is expensive and impractical to allow change data to remain on the database system that is no longer in use. However, the system ensures that the change tables do not grow without limit.
Existing purge mechanisms rely on the conventional SQL DELETE statement, whose performance degrades as the change table grows and as the number of rows to be deleted increases.